After raising the issue of the missing points last week, all my reward points vanished on Monday. They're all back now, with the first ones showing the correct bonus points, either as

"First year welcome bonus"

or

"Outbound spend bonus" for non-uk spend.

The card still shows as Gold Card in the account page, but I'm happy my 20,000 points will trigger now, and I think the more recent grocery shops at Tesco will get the bonus points a couple of days later as expected.